lexipixel - 7:04 pm on Jun 9, 2011 (gmt 0)
In addition to the default TinyMCE editor shipped with WP, you can upgrade it (with the TinyMCE Advanced plugin or manually if you got skills).
BUT ...regardless of which editor you use with WordPress, the output is still filtered and reformatted
The majority of the reformatting is done by the wp-includes/formatting.php file.
How WordPress processes post content is explained here: [codex.wordpress.org...]